Ok, I've added support for safe tasks as an overload. Basically, in
@system mode tasks allow unsafe sharing, but in @safe mode they have the
same requirements as std.concurrency.
I've also added ref return for tasks.
Can we please get this module reviewed? I'd really like to get it into
the next release (i.e. 2.050, not 2.049, which is already in beta.)
On 9/10/2010 9:31 PM, Michel Fortin wrote:
Le 2010-09-10 à 21:01, David Simcha a écrit :
This is getting me thinking. I've given up making most of std.parallelism
safe. Parallel foreach is the hardest thing to make safe, and for me
personally the most useful part of std.parallelism. I wonder, though, if I can
make Task @safe/@trusted provided:
1. The input args are either indirection-free, immutable, or shared.
2. The callable is a function pointer, not a delegate, alias or class with
overloaded opCall.
Couldn't it be a shared delegate too (a delegate to a shared member)?
3. The return type is either indirection-free, immutable or shared. (This is,
unfortunately, necessary b/c the worker thread could in theory hold onto a
reference to it in TLS after returning, even though doing so would be
thoroughly idiotic in most cases.)
I'm thinking I may add a safeTask() function that is marked @trusted, and creates a Task object iff
these constraints are satisfied (and otherwise doesn't compile). I think the only sane way to do
this is to have a separate safe function for creating tasks in addition to the more lenient
"here be dragons" one. The only major thing I don't like about this is the idea of
sprinkling a few safe functions in a mostly "here be dragons" module. It seems like it
would complicate code reviews.
Perhaps the safe parts of tasks and thread pools could be put in
std.concurrency, and the unsafe parts necessary for std.parallelism could be
built on top of it and reside std.parallelism (which could just cast its
delegates to shared delegates to bypass the safeties).
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